Population Ecology Flashcards
(20 cards)
Define population
a group of organisms which are interbreeding and are the same species, living in the same area
What characterizes a given population?
The boundaries that define the area it exists in (both artificial and natural)
What are the 2 focuses of population ecology?
- the number of individuals in an area
- how/why population size changes occur
What does ‘N’ represent in population ecology?
the total number of individuals in a population
What 2 traits are important for describing a population?
- population size (N)
- population density
What is population density?
The number of individuals present in a given area.
- Ex: 5 deer per square km
Which populations are more likely to be stable, and more adaptible: smaller or larger populations?
larger populations
- since they have higher genetic variation (more traits!)
What is a difficulty for low-density populations?
Greater difficulty in finding mates
What does a low-density population look like?
Very spread out
What is the relationship between animal size and their population density?
- smaller animals tend to live at higher density (ex. lots of chipmunks)
- larger animals tend to live at lower density (ex. very few deer)
How do researchers actually find out how many individuals are in a population?
- sample a portion of the population’s habitat
- make inferences about the population as a whole
What determines the number and size of a quadrat used for sampling?
the type of organisms being sampled
- ex, you would need a bigger quadrat for trees than for grasses
What sampling method is used for counting a plant population?
quadrat sampling
What sampling method is used for counting a plant population?
Mark and recapture
What assumption does mark and recapture sampling make?
larger populations will return fewer marked individuals than smaller populations
What are some limitations to mark-recapture surveys?
- some animals are trap happy and keep getting trapped for free food (bait) (this makes the population seem smaller than it is)
- some animals are trap avoidant (makes population seem larger than it is)
- marking might reduce animal survival (ex. a brightly coloured tag reduces camouflage)
What are the three types of dispersion patterns a population might have?
- uniform (ex. penguins are territorial over nesting sites)
- random (ex. dandelions)
- clumped (ex. elephant herds)
What is the purpose of demography?
studying the changes of a population over time
How do you calculate the mortality rate for a life table?
number of individuals dying / number of individuals surviving *100
(or 1000 individuals)
